Hydrogen Peroxide → Ethyl 7-(4-propoxyethoxyphenyl)-1,1-dioxo-2,3-dihydro-1-benzothiepine-4-carboxlate

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Reaction Conditions

Reaction Steps

Ethyl 7-(4-propoxyethoxyphenyl)-2,3-dihydro-1-benzothiepine-4-carboxylate (45 g, 109.1 mmol) was suspended in 405 ml of acetic acid and was heated to 60° C. to dissolve. A solution of 30% hydrogen peroxide (25.35 g, 223.6 mmol) in 45 ml of acetic acid was dropped slowly at 60-70° C. After the dropping, the mixture was stirred at 65-70° C. for 3 hours. At that temperature, 40 ml of an aqueous sodium sulfite solution was dropped and disappearance of the peroxide was checked with iodo-starch paper. After dropping 275 ml of water at that temperature, the mixture was cooled and stirred for 2 hours and then was stirred at 0-10° C. for 30 minutes. After filtration, the residue was washed with an ice-cooled, mixed solution of acetic acid/water (45 ml/31.5 ml) and subsequently with 225 ml of water. After vacuum drying (40° C.), 45.9 g (Yield 94.6%) of ethyl 7-(4-propoxyethoxyphenyl)-1,1-dioxo-2,3-dihydro-1-benzothiepine-4-carboxylate was obtained as white crystals.

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